Used for specific properties like
-elasticity, then comfort close to the back
-transparency, to clearly see the water level inside
-resistance to any liquid, then taste free
-PVC free, then no toxic substances reject when recycled
Thermoplastic polyurethanes are perfect for bladder and tube.

Reusable and collapsible

Reusable and collapsible-

Can be folded and stored into your pocket.
Reduce waste of plastic cup.